tbuckley/cabot-search huggingface dataset:
Abstract P3131: Aquaglyceroporin Expression In Resistance-sized Arteries
Authors: Angela Reinert, Young Choi, Saline Lay, Tiffany Nguyen, Nare Gevorgyan, Simon Bulley
Journal: Circulation Research (2022)

Due to its importance in maintaining homeostasis of many physiological processes in the body, including the cardiovascular system, it’s crucial that humans consume water, to replace any loss that occurs through urine, sweat, feces, and expelled air. Unfortunately, a significant proportion of the global population either does not have a safe drinking water source or consistent access to water throughout the year and with water scarcity projected to only impact more people in the future, it’s important to understand what is the effect of water deprivation on the human body. Once the body loses a greater amount of water than it’s able to intake it enters the process of dehydration, resulting in a body water deficit, known as hypohydration. Even mild dehydration can affect an individual's mental and physical well-being, with an association between chronic dehydration and adverse cardiovascular outcomes, including hypertension, stroke, and coronary heart disease (CHD). While the majority of research is focused on acute dehydration, chronic low water intake, also termed underhydration, is also associated with adverse health outcomes. However, the effect of acute and chronic reductions in water intake on the function of resistance-sized arteries, and particularly vascular smooth muscle cells (VSMCs), that regulate systemic blood pressure, is poorly understood. Aquaporins (AQPs) are membrane proteins primarily responsible for facilitating water movement across cells in tissues and organs, , with the aquaglyceroporin (AQP3, AQP7, AQP9-10), subfamily also exhibiting permeability to glycerol, and other small solutes. Previous studies have identified AQP7 expression in endothelial cells (ECs) and the heart, where it is proposed to enable the uptake of glycerol as a cardiac energy substrate, however, its function in VSMCs is unclear. Preliminary data demonstrate that in mice the expression of glycerol-permeable aquaglyceroporins, AQP7 and AQP9, are elevated in mesenteric arteries by 48 hours of water deprivation and 28 days of reduced water intake, respectively. Mesenteric artery glycerol content is higher in mice dehydrated for 48 hours compared to 0-hr controls. Male mice administered 10% glycerol ad libitum with water have elevated mesenteric artery AQP7 expression when compared to 0-hr controls. In female mice, ovariectomy (OVX) attenuates increased AQP7 expression in 48-hr dehydrated females, with, 17β-estradiol treatment restoring dehydrated-mediated elevations in expression. These findings suggest that mice adjust to alterations in water intake differently short- and long-term, and suggest a potential mechanism for increasing VSMC glycerol-uptake as an energy source during water duress.
Abstract P1084: Mature Ipsc-derived Atrial Cardiomyocytes Show That Saturated Fatty Acids Differentially Modulate Atrial Remodeling In Obesity-induced Atrial Fibrillation Compared To Mono And Poly-unsaturated Fatty Acids.
Authors: Arvind Sridhar, Olivia T Ly, Mahmud Arif Pavel, Hanna Chen, Francisco Gonzalez, Srikanth Perike, Liang Hong, Mark McCauley, Jalees Rehman, Dawood Darbar
Journal: Circulation Research (2022)

Background: Increased free fatty acids (FFA) and FA infiltration, both major hallmarks of obesity can individually modulate changes leading to AF. For example, mass spectrometry on obese mouse heart tissues have shown that saturated FAs (SFA), monounsaturated FAs (MUFA), and polyunsaturated FAs (PUFA) are all significantly increased compared to controls. The highest increase was shown to be in linoleic acid (LA), a PUFA followed by palmitic acid (PA, SFA) and oleic acid (OA, MUFA). Although reports suggest that some FAs induce ventricular arrhythmias in mice, the differential electrophysiological effects of SFAs, MUFAs, and PUFAs on the atria remain unclear. Objective: To determine the individual roles of SFAs, MUFAs, and PUFAs in mediating atrial remodeling in obesity-induced AF using mature human induced pluripotent stem-derived atrial cardiomyocytes (iPSC-aCMs). Methods: We compared iPSC-aCMs and HL-1 cells treated with bovine serum albumin (BSA) with palmitic acid (PA), oleic acid (OA) and LA cells (600 uM each) for 24 hours and 1 week. Ion channel function were assessed using optical voltage mapping and whole-cell patch clamping, and we assessed atrial remodeling using qPCR, and western blotting. Results: iPSC-aCMs treated with PA, OA, and LA displayed higher expression of FABP3 and CPT1A suggesting increased FA metabolism (Figure A-C). In HL1 cells, protein expression of Cpt1a was increased in all groups after FA treatment (Figure D). PA differentially modulated expression of Kv7.1 and NCX1 in HL1 cells (Figure E-F) and ion channel mRNA expression in iPSC-aCMs (Figure G-L). After 1 week PA and LA treatment b-adrenergic signaling was significantly increased in iPSC-aCMs while OA decreased it compared to controls (Figure M-O). Lastly, 24-hour PA, OA, LA treatment differentially modulated the atrial action potential (AP). While PA and LA significantly shorten the action potential, there was no significant changes to the AP after OA treatment. Conclusions: Using mature iPSC-aCMs, we showed for the first time that SFA, MUFA, and PUFA not only increased FA metabolism but differentially affected b-adrenergic signaling and ion channel remodeling leading to differential effects on the atrial AP. Our findings may have important implications for the management of obesity-induced AF in patients.
Abstract P1062: Regional Differences In Sarcomeric Glycogen Synthase Kinase 3β Maintain Normal Chamber Level Function
Authors: Marisa Stachowski-Doll, Michaela Door, Jonathan A Kirk
Journal: Circulation Research (2022)

The structure of the left ventricle is spatially and temporally heterogeneous. The heart’s electrical system helps synchronize these events, but mechanical events play an important role as well. However, experimental evidence of the regional mechanical processes that underpin a “normal contraction” remain largely unknown. Despite the differences in deformation between the anterior and posterior walls, sarcomere lengths during filling and ejection are the same in these regions. One explanation for this disconnect is the myocyte’s force production is different despite similar sarcomere lengths, a relationship known as Length Dependent Activation (LDA). Indeed, a modeling study suggested LDA is a critical regulator of mechanical synchrony in the left ventricle. We recently found the serine/threonine kinase GSK-3β localizes to the z-disc and can modulate LDA, and thus hypothesized it may play a role in maintaining normal cardiac synchrony. We used inducible cardiomyocyte specific GSK-3β KO mice and GSK-3βfl/fl/Cre- littermate Con treated with tamoxifen in which GSK-3β was KO for three weeks. We assessed regional differences in GSK-3β protein levels and found that Con mice had substantial regional heterogeneity: 50% more cytosolic GSK-3β in the posterior wall compared to the anterior wall; however, the myofilament-bound GSK-3β was the opposite, with 50% less GSK-3β in the posterior wall. This regional heterogeneity was lost in KO mice, in which protein levels were homogenously low. There were no differences detected by m-mode echo between Control and KO mice. However, strain analysis revealed a significant interaction (p=0.037) between genotype and region (Anterior vs. Posterior), in which regional differences in Systolic Strain Rate were ablated in the knockout. These data suggest that the regional differences in GSK-3β sarcomeric levels were important for maintaining regional functional heterogeneity. We further observed that sarcomeric GSK-3β levels (but not cytosolic) decreased in a mouse myocardial infarction model, which these findings suggest could worsen mechanical dyssynchrony post-infarct. Perhaps a possible therapy for mechanical dyssynchrony could involve regional restoration of sarcomeric GSK-3β levels to restore synchrony.
Abstract P1056: Stretch Reduces Inter-filament Spacing And Triggers Alterations In Thick-filament Structure In Healthy Left-atrial Fibers
Authors: Weikang Ma, Maria Papadaki, Jonathan A Kirk, Cassady Rupert, Carlos L del Rio, Thomas C Irving
Journal: Circulation Research (2022)

Introduction: Left-atrial dilatation is thought to play a key pathological role in facilitating remodeling in both genetic and acquired cardiac myopathies, as well as enabling the onset and maintenance of atrial fibrillation. However, despite its likely role in disease, the structural responses of the atria to stretch remain understudied. The myofilament responses to stretch have been extensively studied in ventricular tissue, where strain-dependent recruitment of reserve, OFF-state, myosin heads from the thick-filament contribute to length dependent activation (LDA, i.e., greater forcer at longer sarcomere lengths). In these experiments, the effects of stretch in both atrial sarcomere and thick-filament structure were evaluated. Methods: Myofilament structure was evaluated via x-ray diffraction at two sarcomere lengths (SL, SHORT: 2.1 μm, and LONG: 2.3 μm) in relaxed left-atrial and left-ventricular myocardial skinned fibers from Yucatan mini-pigs. In these experiments, both equatorial and meridional reflections reflecting sarcomeric structure and ordering were evaluated. In addition, the biomechanical effects of stretch were also evaluated in both skinned porcine fibers and engineered heart tissues (EHT) from atrial and ventricular hIPSc-derived myocytes via a proprietary system (MyoPod; Propria Biosciences). Results: In both atrial skinned fibers and EHTs, stretch triggered moderate increases in force, demonstrating LDA. LA fibers, stretch decreased lattice spacing but failed to alter the I 11 /I 10 equatorial intensity ratio, suggesting negligible length-dependent recruitment of OFF-state myosin heads from the thick-filament. LA fibers, however, tended to have higher I 11 /I 10 values at short SL (vs. LV fibers) suggesting an intrinsically higher population of ON-state myosin heads. In addition, stretch triggered alterations in thick filament ordering in both LA and LV fibers, as reflected by changes in both the 3 rd and 6 th order meridional reflections (M3 and M6), suggesting effects in both myosin heads and thick-filament backbone. Conclusion: Atrial stretch results in marked sarcomere structural alterations, reducing both inter-filament spacing and thick-filament ordering that likely contribute to length dependent activation. The role of these alteration in atrial pathophysiology remains to be studied
Abstract P1130: A Minimally Invasive Injectable Syncsc Adhesive (misa) For Aging Rats With Chemotherapy-induced Heart Failure
Authors: Ke Huang
Journal: Circulation Research (2022)

Statement of Purpose: Long-term chemotherapy in cancer treatment may lead to serious myocardiopathy that then prompts heart failure (HF) or even death. Additionally, patients over 65 years of age are likely to have complications in other organs, making the treatment an insurmountable obstacle. In previous studies, regenerative therapy has been reported as a robust method to improve HF. Despite the successful proof of concept, one big challenge for clinical translational is to deliver the therapeutics in a minimally invasive way. To that end, we sought to develop a minimal-invasively injectable synthetic cardiac stromal cells (synCSC) adhesive (MISA) that could be delivered with small incisions on the chest wall, without an open-chest surgery. The MISA should be gelatinized easily right after transplantation to increase the retention of synCSCs in the pericardium cavity. To mimic aging patients with cardiomyopathy caused by HF, we have established an aging rat model with HF induced by doxorubicin. The overarching hypothesis is that minimal-invasively delivery of MISA improves synCSC therapeutic efficacy in the aging rat model of HF. Methods: We created an injectable MISA by embedding optimized synCSCs into a myoECM-fibrinogen gel in an adjusted concentration. MISA retains my ECM proteins and peptide fragments while gelatinizing fast after injection. After MISA fabrication, we characterized its 3D morphological features to determine synCSC embedding efficiency. To determine the safety, efficacy, and mechanism of MISA treatment, we employed multiple doxorubicin intraperitoneal injections as an oxidant generator and topoisomerase II inhibitors to create an aging rat model of HF. Results: MISA improved therapeutic efficacy in HF treatment after being injected minimal-invasively. Also, MISA polymerized fast after administration and formation of a thin layer of regenerative gel that released regenerative factors to the myocardium in a sustained release manner while degradation. MISA as therapeutic biologics has the potential to revolutionize cardiovascular regenerative medicine.
Abstract GS101: Myosin Binding Protein H-like Competes With Cardiac Myosin Binding Protein-c To Prolong Atrial Contraction
Authors: Kelly Araujo, Kc Woulfe, Lucas Wittenkeller, David Y Barefield
Journal: Circulation Research (2022)

Myosin binding protein-H like (MyBP-HL) has recently been identified as a novel component of myofilaments in the cardiac atria. Loss of MyBP-HL is associated with dilated cardiomyopathy and arrhythmia in humans and mice. MyBP-HL is highly homologous to cardiac myosin binding protein-C (cMyBP-C), which has been studied in the context of genetic cardiomyopathy. Prior work using mouse atrial tissue lysates established MyBP-HL and cMyBP-C bind competitively and maintain a stoichiometric ratio compared to myosin heavy chain. We now confirm this competitive binding using neonatal rat ventricular cardiomyocytes (NRVMs) transfected with mouse Mybphl . Using confocal microscopy with internal controls, we found a linear, inverse relationshib between myosin binding protein levels with NRVMs with high levels of MyBP-HL expression showing a reduction in cMyBP-C levels compared to untransfected NRVMs that only express cMyBP-C. While we show that these two myosin binding proteins bind comparatively with each other, the functional consequences are unclear. We performed force-calcium measurements of permeabilized single atrial cardiomyocytes and found that loss of MyBP-HL does not significantly alter the calcium sensitivity of force development, or the specific force generated by isometric contraction. Because cMyBP-C is a known regulator of crossbridge sliding velocity, we evaluated contraction and relaxation kinetics of Mybphl single-myofibrils from WT and Mybphl homozygous null mice. Atrial myofibrils lacking Mybphl showed a significantly faster rate and shorter duration of their linear phase of relaxation, which is governed by the off-rate of myosin from actin. This suggests that extra cMyBP-C in the atria can hasten myofibril relaxation. In healthy atria with MyBP-HL replacing approximately half the cMyBP-C, the slow phase of relaxation is prolonged. While the physiological importance of this is not explored, it provides a mechanism by which loss of function mutations in MYBPHL cause contractile dysfunction.
Abstract P2038: Synthetic Membrane Stabilizers Reduce Serum Ck And Immune Cell Infiltrate In Neonatal Mdx Skeletal Muscle Prior To Overt Muscle Necrosis Onset In Vivo
Authors: Houda Cohen, Joseph M Metzger, McKayla Carlson
Journal: Circulation Research (2022)

Duchenne muscular dystrophy (DMD) is a fatal X-linked recessive disease caused by a mutation in the dystrophin gene resulting in a complete loss of dystrophin from the striated muscle. This leads to the disruption of the dystrophin-associated glycoprotein complex and altered mechanical and signaling functions subsequently causing membrane instability, necrosis, and progressive muscle wasting. Immune cell infiltration is a prominent feature of the DMD pathophysiology and is strongly associated with disease severity. To date, no curative treatment is available for DMD. A logical therapeutic approach for DMD is to directly target the primary defect of DMD, sarcolemma instability, and thus prevent contraction-induced membrane damage. First in class synthetic triblock copolymer, poloxamer 188 (P188), is a muscle membrane interfacing and stabilizing molecule that has been shown to protect dystrophic myocardium and skeletal muscle from acute stress induced injury in vivo . Creatine kinase (CK) is a well-established biomarker of DMD that reflects sarcolemma damage, and serum levels have been shown to dramatically increase in mdx mice, but this has not been fully characterized during the early postnatal growth period prior to overt disease onset at 3 weeks. Under standard laboratory housing conditions for adult mdx mice (6-9 month old), we found that daily administration of P188 for two weeks did not significantly change serum CK levels or Evan’s blue dye uptake by diaphragm, heart or tibialis anterior muscles. In order to evaluate P188’s ability to protect dystrophin-deficient striated muscle prior to the overt disease, serum CK levels need to be characterized during this time period to identify the earliest muscle membrane damage event in mdx striated muscle and thus the earliest time point for therapeutic intervention. Results show that mdx serum CK levels are significantly higher than control serum levels 15 days after birth and continue to increase dramatically to 20 days after birth, and then CK remains high for the lifespan. Systemic delivery of P188 to neonatal mdx mice (12 days old) prior to CK peak significantly reduced serum CK levels and blunted immune cell infiltrate as compared to saline control mdx mice. These findings support the hypothesis that early intervention with membrane stabilizers has the potential to mitigate muscle damage and blunt the inflammatory response characteristic of DMD disease pathology. More work must be done to fully understand the early pathophysiological changes associated with dystrophin deficiency in order to implement novel therapeutic strategies including membrane stabilizers to enhance the standard of care for these patients and their families.
Abstract P1120: Project Singular: Building A Large-scale Genetics Dataset To Fuel Research Towards Curative Solutions For Single Ventricle Heart Disease
Authors: Diane M Pickles, Kaitlin Davis, Kirstie Keller
Journal: Circulation Research (2022)

Objective: Single ventricle (SV) heart disease is a set of rare conditions occurring in 5 out of 100,000 births. Forty years ago, such diagnoses were universally fatal, but surgical advances have enabled most patients to live into their thirties. However, SV patients face a lifetime of expensive, invasive clinical care for complications and co-morbidities and decreased life expectancy and quality of life. The cause of SV heart disease is still unknown; believed to be both Mendelian and non-Mendelian, multigenic and multifactorial. To date, four genes have been linked to SV disease; however, the penetrance is low, and none are causal. Project Singular aims to uncover the cause(s) of SV by sequencing at least 5,000 SV patients and immediate family members, in conjunction with collecting important medical data, creating the largest genetic dataset available to date in this disease community and make it available free of charge to all qualified researchers. Methods: Subjects will be recruited and consented virtually through an online portal and will receive a biospecimen collection kit (saliva or buccal) by mail to return to the Broad Institute of MIT and Harvard. Samples will be processed, quality-controlled, and whole genome-sequenced using Illumina HiSeq at 30X coverage, with methylation arrays conducted on a subset. Sequences will be aligned to the human genome, annotated, deidentified, and securely deposited into the Terra.bio platform. Participants will fill out a survey on demographics and medical history, and patients will provide medical records. Deidentified phenotypic and genotypic data will be made available for free to qualified researchers globally. Integration with other SV-related registries will be undertaken where possible to increase the power of the study. Conclusion: Project Singular is the first genetics sequencing initiative of its size and depth focused specifically on SV, the most complex of all congenital heart defects. By enabling patients and families to participate from their homes, Project Singular will reduce barriers of travel and cost to increase diversity of participants. Data democratization of the dataset will fuel discovery in single ventricle etiology and lead to new targeted treatments and potentially curative solutions.
Abstract P2039: The Absence Of Sigmar1 Causes Increased Protein Aggregation And Aggravated Cardiac Dysfunction In R120g- αb-Crystallin Mouse
Authors: Richa Aishwarya, Chowdhury S Abdullah, Naznin Sultana Remex, Sadia S Nitu, Brandon Hartman, Judy A King, Md. Shenuarin Bhuiyan
Journal: Circulation Research (2022)

Background: αB-Crystallin (CryAB) is a molecular chaperone responsible for protecting intermediate filaments by maintaining the structural integrity of the sarcomere. Mutation in CryAB at Arg120Gly (CryAB R120G ) causes the formation of toxic pre-amyloid oligomers and protein aggregation, contributing to cardiac dysfunction. In the event of proteotoxic insult, the chaperone proteins function to prevent the accumulation of protein aggregates. One of the multitasking chaperone proteins abundantly expressed in the heart and known to have molecular roles in the clearance of misfolded protein aggregates is Sigmar1. However, Sigmar1’s role in cardiac proteotoxicity and protein aggregation remains unknown. Hypothesis: We hypothesize that Sigmar1 plays a protective role in the degradation of protein aggregates in the heart. Here, we investigated the functional role of Sigmar1 in misfolded proteins aggregation-induced pathological cardiac remodeling and heart failure in CryAB R120G mice. Methods and Result: We measured the Sigmar1 expression level in CryAB R120G hearts and found that endogenous Sigmar1 protein and transcript levels are substantially reduced in CryAB R120G hearts. To test the functional role of Sigmar1 in a proteotoxic model of heart failure in vivo , we crossed the Sigmar1 knockout mouse with the CryAB R120G mouse to generate Sigmar1 ablated CryAB R120G mouse (CryAB R120G xSigmar1 -/- ). Echocardiographic analysis showed the age-dependent aggravation of cardiac dysfunction in the CryAB R120G xSigmar1 -/- mice compared to CryAB R120G mice. Masson’s Trichrome staining also showed increased cardiac fibrosis in the CryAB R120G xSigmar1 -/- mice hearts. Sigmar1 ablation in CryAB R120G mice hearts resulted in increased protein aggregate content measurement by immunostaining and aggregate size measured by electron microscopy. Sigmar1 siRNA-knockdown in CryAB R120G expressing cardiomyocytes also led to a dramatic increase in aggregate size and content. Conclusion: Overall, we found that Sigmar1 plays a vital role in the degradation of protein aggregates in the heart. Sigmar1 knockdown in CryAB R120G hearts promoted interstitial fibrosis, aggravated ventricular dysfunction, cardiac hypertrophy, and increased protein aggregates.